Saturday, July 20, 2013

Skybolt: The First (and only) USAF ALBM: Air Force work on air launched
ballistic missiles began in earnest by the late 1950s, and was spurred
by several factors. Many (incorrectly) regarded the ballistic missile as
a replacement for manned bombers (just as SAMs were to have replaced
interceptors) but combining the two did have its attractions. ICBMs
could not be recalled after firing, or launched and then kept in a
holding position; bombers had these capabilities, as well as being
capable of use in conventional strikes, and assuming successful
completion of a mission and recovery, could be used again. The aircraft,
however, were increasingly vulnerable to air defenses, whereas missile
warheads were essentially unstoppable. There was a political aspect as
well, as it was becoming apparent that the Navy's Polaris
system had the potential for being an almost invulnerable nuclear
deterrent force, while the Strategic Air Command was restricted to
operating fixed land-based missiles and vulnerable bombers. Developing a
mobile strike force using bombers and ALBMs meant that the USAF would
have a chance to compete with Polaris for defense dollars.

Although
conventional aircraft obviously could not maintain standing patrols for
months at a time as submarines could, SAC's airborne alert program had
much the same effect, using rotating flights to keep a portion of the
force in the air at any given time. There were also long-range plans for
nuclear powered bombers that while not having the on-station endurance
of a submarine, could mount patrols of very long duration while carrying
ALBMs.

Martin's Bold Orion ALBM
prototype program was run in 1959, and used three-stage missiles of
various configurations, with the launch aircraft being a refitted B-47
Stratojet. A series of launches were made, with the final shot being
acknowledged as the first known ASAT test, as the missile's trajectory
came close enough (several miles) to the orbit of an Explorer satellite
that the "bird" could have been destroyed had the Orion been carrying a
warhead.

There was another late 1950s ALBM demonstrator program,
this time using the Convair B-58 Hustler as a launch platform. Lockheed
would design and build the High Virgo demonstrator
missiles, which would be carried and launched from the Hustler's
centerline station, which normally carried the aircraft's fuel/bomb pod.

Like Bold Orion, High Virgo was basically a lash-up of existing
solid-fuel stages. An attempt at an ASAT test is said to have been made
during the High Virgo launches, but apparently did not succeed. Despite
the early work on ALBMs done by Lockheed and Martin, the contract for an
operational-type weapon went to Douglas, in 1960. Developed under the
WS-138 program, the Skybolt was to be a two stage solid-fuel missile
capable of carrying a W59 warhead in a Mk.7 reentry vehicle some 1,500
miles. Launch aircraft would (at least initially) be late-model B-52s,
which would carry four missiles externally with a pair of missiles on
each underwing pylon.

Although Skybolt was intended primarily as a
weapon for the B-52G/H force, refitting older models of the
Stratofortress to carry the missile was also considered. Of SAC's other
bombers, the B-47 was in the process of being retired, the B-58 was not
earmarked as a carrier, and extensive changes to the design would have
been necessary to match the weapon to an operational version of the
B-70.

The British joined the Skybolt program early on; RAF Bomber Command badly
needed such a weapon, as its "V-Bombers" were far fewer in number than
SAC's huge force, and as such needed a standoff weapon to keep the
limited number of aircraft as effective as possible. The Vulcan B.2
would have carried four missiles, and a single B.2 test ship was used to
conduct compatibility and dummy drop tests. The Handley-Page Victor B.2
was another potential carrier, and there was even a proposal for a
missile platform version of the Vickers VC.10 airliner armed with the
Skybolt.

The first Skybolt launch took place on the afternoon of
April 19, 1962, with the B-52 launch aircraft staging from Eglin AFB,
Florida. A single Skybolt was carried under the right wing, with an
inert example fitted on the port launcher. The launch and first stage
ignition took place as planned, but a failure of the second stage meant
that the planned 1,000 mile range for this first shot was not achieved.
The second Skybolt test, on June 29, failed completely when the first
stage did not ignite.

Skybolt's high cost, coupled with the
troubled development program, made it a prime target for cancellation.
During a conference between President Kennedy and British Prime Minister
Harold MacMillan in the Bahamas in December 1962, Kennedy let it be
known that the US would not in the end buy Skybolt for SAC, although the
program could be continued by the British. Becoming the sole customer
for Skybolt would have driven costs too high, and MacMillan settled on
an alternative offered by Kennedy, namely the supply of Polaris SLBMs.

Although
the Polaris decision would preserve Britain's nuclear deterrent, the
fact that a new ALBM would not be forthcoming meant that the V-Bomber
force would have a limited lifespan ahead of it, at least in its original
strategic role. The British-developed Blue Steel ASM would be bought in
limited numbers, but that weapon's range and speed could not compare
with those of Skybolt, and development of a more capable Mk.2 version
had been abandoned. Given the cancellation, there was no justification
seen in proceeding with the Vulcan B.3 design, which could have carried a
triple load of missiles under each wing. However, vestiges of the
Skybolt system were to survive to the end of the Vulcan B.2's service
life in the bomber role, as at least some aircraft had provisions for
the missiles, and these were used to haul conventional weapons to the
Falklands.

Ironically, a final Skybolt test launch in December
was hailed by some as a success, although it was later revealed that the
missile did not carry a representative warhead. There was considerable
political furor over the Skybolt cancellation, especially given the
Kennedy Adminstration's lack of enthusiasm for bomber related programs,
in particular the B-70. Critics contended that without the B-70 or
Skybolt, the future of the manned strategic bomber was in doubt.

In
the late 1970s, nearly two decades after the cancellation of Skybolt,
the USAF was again looking at putting small ballistic missiles on
strategic bombers. Like Skybolt, the Longbow missile was to be a
two-stage weapon, but would be far smaller than the older missile,
although thanks to advances in propellant technology the range would
actually be greater. Although Longbow could have been pushed as part of
the early 1980s US nuclear buildup, the program was not picked up, as
there were other systems such as Pershing II and GLCM that had already
reached the hardware stage.

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